Obligatory Beach Boys reference, but especially Pet Sounds and Surf's Up.
Obligatory Bob Marley reference. Driving around in the summer and having a Marley track pop up on the radio is like driving under a cloud; everything cools off and softens up just a little.
Less obviously, Atom Heart Mother by Pink Floyd. It was in my CD Player for the better part of two summer time road trips, so every time I drive to the beach or whatever, I feel like it needs to be on. And no, not just because of Summer '68, though that's a great track (more 'end of summer' than anything).
Picaresque by The Decemberists, since my girlfriend played that on our first trip to the beach together and we had a great time.
When I was younger, I took a road trip with my parents and we left my two brothers at home, so it was just me. Some time-share thing... anyways, I remember having the whole back seat to myself and listening to Billy Joel's The Bridge on the way home. So that counts, I guess.
Otherwise, just a few assorted summer songs;
Sultans of Swing - Dire Straits
America - Simon and Garfunkel (and Yes' cover of it is great too)
Saturday in the Park - Chicago
Probably a few others I'll remember later...
And of course, for most of my teenage years (93-98, roughly), Pop music was awesome, not the formulaic shit they churn out now. Hootie, Dave Matthews, Gin Blossoms, Oasis, Goo Goo Dolls, stuff like that was perpetually on the radio during summers growing up. Then the local pop station started to go downhill with boy bands and Britney Spears as that sort of shit got popular and I switched back to the old standby; classic rock.
